Light-sensitive materials extensively used in electrophotography include inorganic photoconductive materials such as amorphous selenium, selenium alloys, cadmium sulfide and zinc oxide, and organic photoconductive materials typified by polyvinyl carbazole and derivatives thereof. Organic photoconductive materials have the advantage that they are superior to inorganic photoconductive materials with respect to transparency, film-forming property, flexibility and production rate.
An electrophotographic photoreceptors containing various azo pigments in light-sensitive layers have been recently proposed in, for example, JP-B-60-29108 (the term "JP-B" as used herein means an "examined Japanese patent publication"), JP-B-60-29109, JP-A-60-189759 (the term "JP-A" as used herein means an "unexamined published Japanese patent application), JP-A-61-23155, JP-A-62-139564, JP-A-63-44663, JP-A-61-228453, JP-A-57-116345, JP-A-56-143437, JP-A-61-129653, JP-A-58-194035, JP-A-60-196770 and JP-A-63-38945).
However, the performance of electrophotographic photoreceptors using the so far proposed azo pigments is not completely satisfactory with respect to photosensitivity, chargeability and durability.
Further, those photoreceptors cannot be used satisfactorily with printers and other equipment that employ a semiconductor laser as a light source.